one test area was irradiated (5 J/cm2, as measured in
the UVA range). The other non-irradiated area served
as a control. Test reactions were recorded 24 h, 48 h
and 72 h after irradiation. Any reaction (erythema,
oedema or pigmentation) was recorded. The number
of panellists who developed a positive reaction was
expressed as ratio of positivity